1. Field of the Invention
The present invention generally relates to a system and a method for mitigation of induced acceleration to an occupant of a vehicle seat.
2. Background Art
In order to provide an acceptable level of protection to vehicle occupants when the vehicle encounters an explosive event (e.g., a severe acceleration or shock to the vehicle, generally in an upward direction relative to the normal operating position of the vehicle) generated by a land mine, improvised explosive device (IED), and the like, measures are taken to reduce probability and severity of occupant injuries. Many approaches to occupant acceleration reduction provide for the occupant to move downward (as the rest of the vehicle generally moves upward relative to the normal operating position of the vehicle) during the explosive event. The relative downward movement of the occupant typically limits shock loads or spreads the acceleration over an extended period of time relative to the explosive event, thus reducing loads and accelerations to the occupant.
In one example (a M-1114 High Mobility Multipurpose Wheeled Vehicle, HMMWV), a load limiting seat mounting bracket assembly is employed. The bracket assembly plastically deforms at a predetermined load (e.g., design limit). Any force in excess of the design limit moves the seat downward (relative to the normal operating orientation of the vehicle) against the resistive force of the deforming material, thus limiting the load transfer from the vehicle to the occupant to a predetermined maximum value (i.e., level, amount, etc.). The load limiting seat mounting bracket assembly is generally implemented as an “accordion” shaped deformable structure that provides cost, weight and space advantages over alternative conventional approaches.
On the HMMWV vehicle the batteries are located in a box beneath the right front (i.e., commander's) seat. As such, the load limiting seat mounting bracket assembly can not be effectively implemented when the batteries remain located at the normal position beneath the right front seat. Thus, on the M-1114 the battery box is relocated (i.e., lowered) to provide adequate clearance for implementation of the explosive event protective load limiting seat mounting bracket assembly. While lowering the battery container provides room for the seat movement when the seat bracket assembly deforms, lowering the battery container has the deficiency of negatively impacting the ground clearance of the vehicle and thus mobility of the vehicle. Further, lowering the battery container has an additional deficiency of being a more involved and complex procedure than is desirable for kit installation or retrofitting.
Thus, there exists a need and an opportunity for an improved system and a method for mitigation of induced acceleration (e.g., acceleration due to a land mine explosion and the like) to an occupant of a vehicle seat. Such an improved system and method may overcome one or more of the deficiencies of conventional approaches.